Thanks for all of the input guys! I knew this was going to be a tough decision to make give the sheer quantity of different types of monitors being produced these days. Fortunately I live in Chicago and you can find almost every hifi manufacturer's gear at one of the dealers in town.
I will admit, I always have been intrigued with the British manufacturers mentioned (ProAc, Harbeth). The way their sound in described (good timing, fluid, etc) has tended to be how I prefer my system.
That's why I've always loved Muse gear. Some people say the gear is on the "soft" side, but it's just so fluid and listenable. It's like great tube gear without the hassle, and it's really reasonably priced for what it is on the used market.
Other gear that I've owned and initially enjoyed (monitor audio, cambridge audio) just sounded way too fatiguing after awhile. The soundstaging, resolution and air was really nice, but after while it just didn't matter as much to me.